1 /* 2 * Copyright (C)2002 USAGI/WIDE Project 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 * 18 * Authors 19 * 20 * Mitsuru KANDA @USAGI : IPv6 Support 21 * Kazunori MIYAZAWA @USAGI : 22 * Kunihiro Ishiguro <kunihiro@ipinfusion.com> 23 * 24 * This file is derived from net/ipv4/esp.c 25 */ 26 27 #include <linux/module.h> 28 #include <net/ip.h> 29 #include <net/xfrm.h> 30 #include <net/esp.h> 31 #include <asm/scatterlist.h> 32 #include <linux/crypto.h> 33 #include <linux/kernel.h> 34 #include <linux/pfkeyv2.h> 35 #include <linux/random.h> 36 #include <net/icmp.h> 37 #include <net/ipv6.h> 38 #include <net/protocol.h> 39 #include <linux/icmpv6.h> 40 41 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 42 { 43 int err; 44 int hdr_len; 45 struct ipv6hdr *top_iph; 46 struct ipv6_esp_hdr *esph; 47 struct crypto_tfm *tfm; 48 struct esp_data *esp; 49 struct sk_buff *trailer; 50 int blksize; 51 int clen; 52 int alen; 53 int nfrags; 54 55 esp = x->data; 56 hdr_len = skb->h.raw - skb->data + 57 sizeof(*esph) + esp->conf.ivlen; 58 59 /* Strip IP+ESP header. */ 60 __skb_pull(skb, hdr_len); 61 62 /* Now skb is pure payload to encrypt */ 63 err = -ENOMEM; 64 65 /* Round to block size */ 66 clen = skb->len; 67 68 alen = esp->auth.icv_trunc_len; 69 tfm = esp->conf.tfm; 70 blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4); 71 clen = ALIGN(clen + 2, blksize); 72 if (esp->conf.padlen) 73 clen = ALIGN(clen, esp->conf.padlen); 74 75 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 76 goto error; 77 } 78 79 /* Fill padding... */ 80 do { 81 int i; 82 for (i=0; i<clen-skb->len - 2; i++) 83 *(u8*)(trailer->tail + i) = i+1; 84 } while (0); 85 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 86 pskb_put(skb, trailer, clen - skb->len); 87 88 top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len); 89 esph = (struct ipv6_esp_hdr *)skb->h.raw; 90 top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph)); 91 *(u8*)(trailer->tail - 1) = *skb->nh.raw; 92 *skb->nh.raw = IPPROTO_ESP; 93 94 esph->spi = x->id.spi; 95 esph->seq_no = htonl(++x->replay.oseq); 96 xfrm_aevent_doreplay(x); 97 98 if (esp->conf.ivlen) 99 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 100 101 do { 102 struct scatterlist *sg = &esp->sgbuf[0]; 103 104 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 105 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 106 if (!sg) 107 goto error; 108 } 109 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 110 crypto_cipher_encrypt(tfm, sg, sg, clen); 111 if (unlikely(sg != &esp->sgbuf[0])) 112 kfree(sg); 113 } while (0); 114 115 if (esp->conf.ivlen) { 116 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 117 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 118 } 119 120 if (esp->auth.icv_full_len) { 121 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 122 sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 123 pskb_put(skb, trailer, alen); 124 } 125 126 err = 0; 127 128 error: 129 return err; 130 } 131 132 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 133 { 134 struct ipv6hdr *iph; 135 struct ipv6_esp_hdr *esph; 136 struct esp_data *esp = x->data; 137 struct sk_buff *trailer; 138 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 139 int alen = esp->auth.icv_trunc_len; 140 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 141 142 int hdr_len = skb->h.raw - skb->nh.raw; 143 int nfrags; 144 int ret = 0; 145 146 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 147 ret = -EINVAL; 148 goto out; 149 } 150 151 if (elen <= 0 || (elen & (blksize-1))) { 152 ret = -EINVAL; 153 goto out; 154 } 155 156 /* If integrity check is required, do this. */ 157 if (esp->auth.icv_full_len) { 158 u8 sum[esp->auth.icv_full_len]; 159 u8 sum1[alen]; 160 161 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 162 163 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 164 BUG(); 165 166 if (unlikely(memcmp(sum, sum1, alen))) { 167 x->stats.integrity_failed++; 168 ret = -EINVAL; 169 goto out; 170 } 171 } 172 173 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 174 ret = -EINVAL; 175 goto out; 176 } 177 178 skb->ip_summed = CHECKSUM_NONE; 179 180 esph = (struct ipv6_esp_hdr*)skb->data; 181 iph = skb->nh.ipv6h; 182 183 /* Get ivec. This can be wrong, check against another impls. */ 184 if (esp->conf.ivlen) 185 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 186 187 { 188 u8 nexthdr[2]; 189 struct scatterlist *sg = &esp->sgbuf[0]; 190 u8 padlen; 191 192 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 193 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 194 if (!sg) { 195 ret = -ENOMEM; 196 goto out; 197 } 198 } 199 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 200 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 201 if (unlikely(sg != &esp->sgbuf[0])) 202 kfree(sg); 203 204 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 205 BUG(); 206 207 padlen = nexthdr[0]; 208 if (padlen+2 >= elen) { 209 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 210 ret = -EINVAL; 211 goto out; 212 } 213 /* ... check padding bits here. Silly. :-) */ 214 215 pskb_trim(skb, skb->len - alen - padlen - 2); 216 ret = nexthdr[1]; 217 } 218 219 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - hdr_len; 220 221 out: 222 return ret; 223 } 224 225 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 226 { 227 struct esp_data *esp = x->data; 228 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 229 230 if (x->props.mode) { 231 mtu = ALIGN(mtu + 2, blksize); 232 } else { 233 /* The worst case. */ 234 u32 padsize = ((blksize - 1) & 7) + 1; 235 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize; 236 } 237 if (esp->conf.padlen) 238 mtu = ALIGN(mtu, esp->conf.padlen); 239 240 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 241 } 242 243 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 244 int type, int code, int offset, __u32 info) 245 { 246 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 247 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 248 struct xfrm_state *x; 249 250 if (type != ICMPV6_DEST_UNREACH && 251 type != ICMPV6_PKT_TOOBIG) 252 return; 253 254 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 255 if (!x) 256 return; 257 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 258 ntohl(esph->spi), NIP6(iph->daddr)); 259 xfrm_state_put(x); 260 } 261 262 static void esp6_destroy(struct xfrm_state *x) 263 { 264 struct esp_data *esp = x->data; 265 266 if (!esp) 267 return; 268 269 crypto_free_tfm(esp->conf.tfm); 270 esp->conf.tfm = NULL; 271 kfree(esp->conf.ivec); 272 esp->conf.ivec = NULL; 273 crypto_free_tfm(esp->auth.tfm); 274 esp->auth.tfm = NULL; 275 kfree(esp->auth.work_icv); 276 esp->auth.work_icv = NULL; 277 kfree(esp); 278 } 279 280 static int esp6_init_state(struct xfrm_state *x) 281 { 282 struct esp_data *esp = NULL; 283 284 /* null auth and encryption can have zero length keys */ 285 if (x->aalg) { 286 if (x->aalg->alg_key_len > 512) 287 goto error; 288 } 289 if (x->ealg == NULL) 290 goto error; 291 292 if (x->encap) 293 goto error; 294 295 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 296 if (esp == NULL) 297 return -ENOMEM; 298 299 if (x->aalg) { 300 struct xfrm_algo_desc *aalg_desc; 301 302 esp->auth.key = x->aalg->alg_key; 303 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 304 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 305 if (esp->auth.tfm == NULL) 306 goto error; 307 esp->auth.icv = esp_hmac_digest; 308 309 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 310 BUG_ON(!aalg_desc); 311 312 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 313 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 314 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 315 x->aalg->alg_name, 316 crypto_tfm_alg_digestsize(esp->auth.tfm), 317 aalg_desc->uinfo.auth.icv_fullbits/8); 318 goto error; 319 } 320 321 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 322 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 323 324 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 325 if (!esp->auth.work_icv) 326 goto error; 327 } 328 esp->conf.key = x->ealg->alg_key; 329 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 330 if (x->props.ealgo == SADB_EALG_NULL) 331 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 332 else 333 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 334 if (esp->conf.tfm == NULL) 335 goto error; 336 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 337 esp->conf.padlen = 0; 338 if (esp->conf.ivlen) { 339 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 340 if (unlikely(esp->conf.ivec == NULL)) 341 goto error; 342 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 343 } 344 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 345 goto error; 346 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 347 if (x->props.mode) 348 x->props.header_len += sizeof(struct ipv6hdr); 349 x->data = esp; 350 return 0; 351 352 error: 353 x->data = esp; 354 esp6_destroy(x); 355 x->data = NULL; 356 return -EINVAL; 357 } 358 359 static struct xfrm_type esp6_type = 360 { 361 .description = "ESP6", 362 .owner = THIS_MODULE, 363 .proto = IPPROTO_ESP, 364 .init_state = esp6_init_state, 365 .destructor = esp6_destroy, 366 .get_max_size = esp6_get_max_size, 367 .input = esp6_input, 368 .output = esp6_output 369 }; 370 371 static struct inet6_protocol esp6_protocol = { 372 .handler = xfrm6_rcv, 373 .err_handler = esp6_err, 374 .flags = INET6_PROTO_NOPOLICY, 375 }; 376 377 static int __init esp6_init(void) 378 { 379 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 380 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 381 return -EAGAIN; 382 } 383 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 384 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 385 xfrm_unregister_type(&esp6_type, AF_INET6); 386 return -EAGAIN; 387 } 388 389 return 0; 390 } 391 392 static void __exit esp6_fini(void) 393 { 394 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 395 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 396 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 397 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 398 } 399 400 module_init(esp6_init); 401 module_exit(esp6_fini); 402 403 MODULE_LICENSE("GPL"); 404